EP0910586B1 - Process for preparing an aqueous polymer dispersion - Google Patents

Description

The present invention relates to a method of manufacture an aqueous polymer dispersion by radically initiated Polymerization of compounds which can be polymerized by free radicals, their individual solubility in water under the conditions (pressure, Temperature) of the radical-initiated polymerization at least 0.001 wt .-%, based on the respective saturated aqueous solution, (Compounds I), its dispersed Polymer particles in addition to the compounds I at least one Compound II, its solubility in water under the conditions (Pressure, temperature) of the radical-initiated polymerization less than 0.001% by weight, based on the respective saturated is aqueous solution, which consists of a mixture consisting of a part of the compounds I and the at least a compound II, an aqueous oil (disperse phase) in water (Continuous phase) emulsion I produced, the disperse phase consists mainly of droplets with a diameter ≤ 500 nm and in which the polymerization vessel under continuous radical polymerization at least part of the aqueous Emulsion I feeds continuously.

Aqueous polymer dispersions are fluid systems which as disperse phase in aqueous dispersion medium polymer particles contained in a stable disperse distribution. The diameter the polymer particles are generally mainly in the range of 0.01 to 5 µm, often mainly in the range of 0.01 to 1 µm.

Just like polymer solutions when the solvent evaporates, exhibit aqueous polymer dispersions on evaporation of the aqueous dispersion medium has the property of polymer films form, which is why aqueous polymer dispersions in multiple Manner as a binder, e.g. for paints or masses for coating leather, find application.

Aqueous polymer dispersions are usually produced by radical aqueous macroemulsion polymerization of radical polymerizable compounds, which are of minor quantities that may also be used to the molecular weight regulating compounds (hereinafter Molecular Weight Regulator), usually around having at least one ethylenically unsaturated group Monomers (often abbreviated to monomers below).

The monomers to be polymerized, and optionally also used molecular weight regulators, without great effort, e.g. by conventional stirring, emulsified in an aqueous medium and with the addition of free radicals dissolving in the aqueous medium Polymerization initiators polymerized. The term Emulsion expresses that a system of two does not or there is only a little soluble liquid in which the Liquids are present in more or less fine distribution. The liquid present in excess is called continuous or outer phase and the discontinuous Phase droplet-like liquid becomes disperse phase called. An aqueous emulsion is then usually used spoken when the aqueous phase is the continuous phase forms. It usually takes to make an emulsion the addition of emulsifiers (Ullmanns encyclopedia of technical Chemistry, Vol. 10, 4th edition, Verlag Chemie, Weinheim (1975), P. 449), which happens to be the direct union of two colliding liquid droplets of the disperse distribution prevent. The prefix "macro" expresses that it is the aqueous monomer emulsion is one whose disperse phase mainly due to the low distribution effort consists of droplets with a diameter ≥ 1000 nm.

Essential feature of radical aqueous macroemulsion polymerization is now that each of the monomers to be polymerized under the conditions (pressure, temperature) of the radical aqueous macroemulsion polymerization in water a certain solubility having. That in the outer aqueous phase of the aqueous Macromonomer emulsion dissolved polymerization initiator so dissolved in large numbers in the same outer aqueous phase Monomers available as reactants. Above one critical oligomer radicals fall in critical chain length from (homogeneous nucleation) and form primary particles. Is the rate of radical capture by such primary particles the polymer particle formation phase is equal to the rate of radical formation essentially ended and it the polymer particle growth phase follows. In this the monomers diffuse from the dispersed monomer droplets through the water phase into the polymer primary particles, where it is polymerized by the captured radicals and attached to the Primary particles are bound. The regulating the molecular weight Compounds behave essentially like monomers and differ essentially from the monomers only in that they are normally not ethylenically unsaturated Have double bond and therefore not the polymerization chain are able to maintain, but abort them.

Since the homogeneous nucleation is a stochastic process, is their reproducibility is unsatisfactory. Usually increased one therefore in the radical aqueous macroemulsion polymerization that contained in the aqueous macromonomer emulsion Amount of emulsifier to values above the critical micelle formation concentration and thus offers in the outer aqueous phase large reproducible number of micellar locations, whereby the homogeneous nucleation can be suppressed. The Because of their large surface area, micelles capture the oligomer radicals and act in a similar way to that Primary particles as the polymerization centers (heterogeneous Nucleation), the ratio of the amount of monomers to be polymerized and offered micelles essentially the diameter the resulting, immediately disperse distribution resulting polymer particles determined. The part of the large monomer droplets offered is in Compared to the surface of the small micelles, much smaller and is essentially unable to trap oligomer radicals.

In other words, the radical is aqueous Macro emulsion polymerization the polymerization sites outside the dispersed monomer droplets in the aqueous phase and the dispersed monomer droplets only function as a monomer reservoir from which the polymerization sites supplied with monomers by diffusion over the aqueous phase become.

However, this principle reaches its limits if, in addition to monomers polymerizable with the free radical aqueous macroemulsion polymerization, monomers such as stearyl acrylate or vinyl stearate are to be polymerized in, the solubility of which under polymerization conditions in water is <0.001% by weight, based on the saturated aqueous solution ( Moore estimated the solubility of vinyl stearate in water [see J. Polym. Sci., Part A-1, 1967.5, 2665] to be 10 ^-10 mol / dm ³ ). Because of their inadequate solubility in water, such monomers cannot be transported at a sufficient speed to the polymerization sites in the continuous aqueous phase in the case of free-radical aqueous macroemulsion polymerization. They therefore remain as residual droplets of the original monomer droplets and are essentially not incorporated into the polymer particles. However, the copolymerization of such hydrophilic monomers is frequently desired in order to give the films of the resulting aqueous polymer dispersion a profile of properties that is as hydrophobic as possible.

The fact that in radical aqueous macroemulsion polymerization those dispersed in the aqueous medium Monomer droplets are not the actual polymerization sites are noticeable even if in the aqueous polymer dispersion slightly water-soluble organic Tools such as Plasticizer, stickiness improver the resulting filming, film-forming aids or other organic additives are to be incorporated.

These substances are usually with the monomer phase tolerated, you work them before the start of radical aqueous macroemulsion polymerization in the same, remain also as residual droplets of the original monomer droplets back and form in the resulting aqueous polymer dispersion separate particles that differ in their mass density and Size of the polymer particles formed is usually considerable distinguish what about sedimentation, flotation and / or Symptoms of coagulation. However, would be desirable a stay of these additives in the dispersed polymer particles yourself what yourself. usually through an ex post Incorporation of such additives into the finished aqueous Polymer dispersion can not be achieved.

The radical problems identified above Aqueous macroemulsion polymerization can be carried out in a manner known per se How to help by taking special measures the size of the monomer droplets in the aqueous monomer (and optionally additive) emulsion reduced so far that this Droplets predominantly have a diameter of ≤ 500 nm. Measured simultaneously the amount of emulsifier so that in an aqueous medium If there is essentially no micelle formation, the oligomer radicals of the small, a comparatively large total surface having monomer droplets and the Polymerization takes place in the monomer droplets themselves.

Derived from the small size of the monomer droplets this way of radical aqueous emulsion polymerization as a radical aqueous mini-emulsion polymerization and the aqueous starting emulsion as a monomer miniemulsion designated. According to the method of radical aqueous mini-emulsion polymerization can also be particularly hydrophobic Monomers (e.g. also macromonomers (such as oligopropene acrylates) Oligomers or polymers containing at least one ethylenically unsaturated Have double bond) copolymerize easily. If other hydrophobic additives are worked in advance of production of the aqueous monomer miniemulsion into those to be polymerized With monomers, these additives are advantageous also in the dispersed polymer particles in chemical and / or contain physically bound form.

The aforementioned hydrophobic components act in the course but not the radical aqueous mini-emulsion polymerization not only disadvantageous, but influence their course normally positive, in which they have the so-called Ostwald ripening reduce. This means the process by which the smaller ones Monomer droplets due to their increased radius of curvature and the resulting increased diffusion pressure monomers lose to the larger monomer droplets. Another advantage the radical aqueous miniemulsion polymerization in that by adjusting the droplet size aqueous monomer miniemulsion in a simple manner the size of the resulting regulating polymer particle diameter, because the latter essentially correspond to the droplet size. Frequently the predominant diameters of the aqueous monomer miniemulsion above 40 nm. The droplet diameter range is favorable from 100 nm to 300 nm, or from 100 nm to 200 nm. This distinguishes the free radical aqueous miniemulsion polymerization significantly from the radical aqueous Suspension polymerization, where from an aqueous monomer emulsion with a monomer droplet size ≥ 0.01 mm becomes. Furthermore, for the radical aqueous suspension polymerization such radical polymerization initiators are mandatory are used, which are preferably not in continuous aqueous medium, but directly in the Dissolve monomer droplets yourself. While such can be considered oil-soluble radical polymerization initiators called starters also for free radical aqueous miniemulsion polymerization are used, but they are to carry them out less preferred. This is because their preferred stay in the monomer droplet the local radical concentration in the same is usually comparatively high. This promotes termination reactions of the radical chain as well as the radical recombination, whereby the achievable polymeric molecular weight and the rate of polymerization decreased become.

Advantageous in the radical aqueous mini-emulsion polymerization is also that they are relatively low emulsifier manufacturing (The critical micelle concentration does not have to be exceeded are) finely divided aqueous polymer dispersions enables.

Prerequisite for an ideal success of a radical aqueous miniemulsion polymerization is that more or less in all monomer droplets of the aqueous monomer miniemulsion the radical polymerization is triggered simultaneously. If this requirement is not met, they will not function started monomer droplets as with the radical aqueous Macroemulsion polymerisation as a monomer reservoir for the started monomer droplets. This changes their composition, which in the case of their subsequent initiation to inconsistencies in the composition of the resulting polymer particles can lead. In the worst case, they remain hydrophobic droplet components as residual droplets and cause Coagulation or creaming etc.

In order to take these relationships into account, the radical aqueous mini-emulsion polymerization mostly in batch form carried out. That is, the aqueous monomer miniemulsion is generated, placed in the polymerization vessel, to the polymerization temperature warmed and then with stirring a sufficient amount of free radical aqueous polymerization initiator transferred (see e.g. P. Rajatapiti, V.L. Dimonie, M.S. El-Aasser, Polymeric Materials Science and Engineering, Proc. of the ACS Division of Polymeric Materials Science and Engineering, 71 (1994), pp. 57 to 59; Journal of Applied Polymer Science, Vol. 49, pp. 633-655 (1993); EP-A 520478; EP-A 401 565;).

However, the problem with all radical polymerizations of monomers having at least one ethylenically unsaturated group is that they are extremely exothermic. For reasons of a more reliable control of the reaction, they are therefore generally very difficult to carry out in batch form.
Rather, the feed procedure is preferred in which the monomers to be polymerized by free radicals are continuously fed to the polymerization zone with continuous polymerization in accordance with their consumption.

If you lead a polymerization zone with continuous polymerization an aqueous monomer miniemulsion according to their Consumption steadily increases, so hit at a later date supplied monomer droplets always on already radical initiated monomer droplets. The former therefore act for the latter as a monomer reservoir until the former itself be initiated. This leads to the disadvantages already described.

DE-A 40 25 290 tries to counter this problem by that it uses an oil-soluble polymerization initiator that in advance of the preparation of the aqueous monomer miniemulsion in the Monomers is dissolved.

However, such a procedure is extremely risky and in a large-scale implementation is hardly justifiable.

Another disadvantage of a pure monomer miniemulsion feed procedure is because the flow resistance of a aqueous monomer miniemulsion due to the small monomer droplet diameter with increasing proportion by weight of the emulsified Monomers growing strongly. Monomer weight percentages above 50% by weight are therefore hardly conceivable. This limits in correspondingly the possible solid volume fraction of the resulting aqueous polymer dispersion.

The object of the present invention was therefore a Free radical aqueous miniemulsion polymerization process, in that of the polymerization zone with continuous polymerization at least part of the aqueous monomer miniemulsion continuously supplied to provide that the disadvantages of the prior art methods in one has a lesser extent.

Accordingly, a process for producing an aqueous Polymer dispersion through radical-initiated polymerization of radically polymerizable compounds their individual Solubility in water under the conditions (pressure, temperature) the radical-initiated polymerization at least 0.001 wt .-%, based on the respective saturated aqueous Solution, is (compounds I), the dispersed polymer particles in addition to the compounds I, at least one compound II, their solubility in water under the conditions (Pressure, temperature) of the radical-initiated polymerization less than 0.001% by weight, based on the respective saturated is aqueous solution, which consists of a mixture consisting of a molar amount B of the compounds I and at least one compound II, an oil (disperse phase) in water (Continuous phase) emulsion I, whose disperse Phase consists mainly of droplets with a diameter ≤ 500 nm and in which the polymerization vessel under continuous radical polymerization at least part of the continuously feeding aqueous emulsion I as a feed I, found, which is characterized in that the continuous Inlet I accompanied by at least one inlet II synchronously, with the proviso that the at least one inlet II Feed a molar amount A of the compounds I and / or an oil (disperse phase) in water (continuous phase) Emulsion II is a molar amount A of the compounds I, the disperse Phase mainly from droplets with a diameter ≥ 1000 nm exists and the molar amount A 5 to 300% of the molar amount B is.

Suitable compounds I are all those monomers which have at least one ethylenically unsaturated group and are customarily used in the context of free-radical aqueous macroemulsion polymerization. These monomers include olefins such as ethylene, vinyl aromatic monomers such as styrene, α-methylstyrene, o-chlorostyrene or vinyl toluenes, vinyl and vinylidene halides such as vinyl and vinylidene chloride, esters from vinyl alcohol and monocarboxylic acids containing 1 to 12 carbon atoms such as vinyl acetate, vinyl propionate , Vinyl n-butyrate, vinyl laurate and commercially available monomers VEOVA® 9-11 (VEOVA X is a trade name of Shell and stands for vinyl esters of carboxylic acids, which are also referred to as Versatic® X acids), esters from allyl alcohol and Monocarboxylic acids having 1 to 12 carbon atoms, such as allyl acetate, allyl propionate, allyl n-butyrate and allyl laurate, esters of α, β-monoethylenically unsaturated mono- and dicarboxylic acids preferably having 3 to 6 carbon atoms, such as, in particular, acrylic acid, methacrylic acid, maleic acid , Fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as bes onders acrylic acid and methacrylic acid methyl, ethyl, n-butyl, isobutyl and -2-ethylhexyl ester, maleic acid dimethyl ester or maleic acid n-butyl ester, nitriles α, β-monoethylenically unsaturated carboxylic acids such as acrylonitrile and C _{4- 8-} conjugated dienes such as 1,3-butadiene and isoprene.

The monomers mentioned generally form the main monomers, which, based on the total amount of the monomers to be polymerized, normally more than 50% by weight unite. Compounds I that polymerize on their own usually Homopolymers result in increased water solubility usually only be used as modifiers Monomers in amounts based on the total amount to be polymerized Monomers, less than 50% by weight, usually 0.5 up to 20, preferably 1 to 10 wt .-%, co-polymerized.

Examples of such monomers are 3 to 6 carbon atoms α, β-monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as Acrylic acid, methacrylic acid, maleic acid, Fumaric acid, itaconic acid, acrylamide and methacrylamide, further Vinyl sulfonic acid and its water-soluble salts and N-vinyl pyrrolidone.

Monomers, which usually increase the internal strength of the films of the aqueous polymer dispersions, are generally also co-polymerized only in minor amounts, usually 0.5 to 10% by weight, based on the total amount of the monomers to be polymerized. Such monomers normally have an epoxy, hydroxy, N-methylol, carbonyl or at least two non-conjugated ethylenically unsaturated double bonds. Examples include N-alkylolamides of α, β-monoethylenically unsaturated carboxylic acids having 3 to 10 carbon atoms and their esters with alkanols having 1 to 4 carbon atoms, among which the N-methylolacrylamide and the N-methylolmethacrylamide are very particularly preferred, two monomers having vinyl radicals, two monomers having vinylidene radicals and two monomers having alkenyl radicals. The di-esters of dihydric alcohols with α, β-monoethylenically unsaturated monocarboxylic acids are particularly suitable, among which in turn acrylic and methacrylic acid are preferably used. Examples of such monomers having two non-conjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate and 1,4-butylene glycol diacrylate as well as propylene glycol diacrylate, dicinylbenzene, vinylamethacrylate, methacrylate, methacrylate, methacrylate, methacrylate, methacrylate, methacrylate, methacrylate Cyclopentadienyl acrylate or triallyl cyanurate. In this context, the methacrylic acid and acrylic acid C ₁ -C ₈ hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate as well as compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate are also of particular importance.

In addition to ethylenically unsaturated double bonds Monomers can the compounds I in minor amounts, usually 0.01 to 2 wt .-%, based on those to be polymerized Monomers, the radical polymerizations Molecular weight regulating substances such as mercaptans, e.g. tert-dodecyl mercaptan or 3-mercaptopropyltrimethoxysilane.

A) 80 bis 100 Gew.-Teilen wenigstens eines Monomeren aus der Gruppe umfassend Styrol, α-Methylstyrol, Vinyltoluole, Ester aus 3 bis 6-C-Atome aufweisenden α,β-monoethylenisch ungesättigten Carbonsäuren und 1 bis 12 C-Atome aufweisenden Alkanolen, Butadien sowie Vinyl- und Allylester von 1 bis 12 C-Atome aufweisenden Alkancarbonsäuren (Monomere A) und

B) 0 bis 20 Gew.-Teilen sonstigen, wenigstens eine ethylenisch ungesättigte Gruppe aufweisenden Verbindungen I (Monomere B)

sowie gegebenenfalls 0,01 bis 2 Gew.-%, bezogen auf die Summe aus den Monomeren A und B, an das Molekulargewicht regelnden Verbindungen I bestehen.Thus, the compounds I can, for example

A) 80 to 100 parts by weight of at least one monomer from the group comprising styrene, α-methylstyrene, vinyl toluenes, esters of 3 to 6 C-atom-containing α, β-monoethylenically unsaturated carboxylic acids and 1 to 12 C-atom alkanols , Butadiene and vinyl and allyl esters of alkanecarboxylic acids (monomers A) having 1 to 12 carbon atoms and

B) 0 to 20 parts by weight of other compounds I (monomers B) which have at least one ethylenically unsaturated group

and optionally 0.01 to 2% by weight, based on the sum of the monomers A and B, of the compounds I regulating the molecular weight.

Possible monomers A are e.g. n-butyl acrylate, 2-ethylhexyl acrylate, Methyl methacrylate and styrene.

Possible monomers B are acrylamide, methacrylamide, acrylic acid, Acrylonitrile, methacrylonitrile, 2-acrylamido-2-methylpropanesulfonic acid, Vinyl pyrrolidone, hydroxyethyl acrylate, hydroxymethyl acrylate, Hydroxypropyl acrylate, hydroxypropyl methacrylate, quaternized Vinylimidazole, N, N-dialkylaminoalkyl (meth) acrylates, N, N-Dialkylaminoalkl (meth) acrylamides, trialkylammoniumalkyl (meth) acrylates and trialkylammonium alkyl (meth) acrylamides. (Meth) acrylic is a shortening for methacrylic or acrylic.

• 70 bis 100 Gew.-% aus Estern der Acryl- und/oder Methacrylsäure mit 1 bis 12 C-Atome aufweisenden Alkanolen und/oder Styrol,

oder zu

• 70 bis 100 Gew.-% aus Styrol und/oder Butadien,

oder zu

• 70 bis 100 Gew.-% aus Vinylchlorid und/oder Vinylidenchlorid,

oder zu

• 40 bis 100 Gew.-% aus Vinylacetat, Vinylpropionat und/oder Ethylen

zusammengesetzt sind.However, embodiments according to the invention are also those in which the compounds I are

• 70 to 100% by weight of esters of acrylic and / or methacrylic acid with alkanols and / or styrene having 1 to 12 carbon atoms,

or to

• 70 to 100% by weight of styrene and / or butadiene,

or to

• 70 to 100% by weight of vinyl chloride and / or vinylidene chloride,

or to

• 40 to 100 wt .-% of vinyl acetate, vinyl propionate and / or ethylene

are composed.

Often the choice of monomer composition is made within of the aforementioned composition grid so that the glass transition temperature values (DSC, midpoint temperature) of the resulting Polymers when the compounds I are polymerized alone below 50 ° C or below 30 ° C, often below 20 ° C and in many cases would also be below 0 ° C (down to -70 ° C).

The compounds II can also be monoethylenically unsaturated Have groups. In this case, they are the ones to be polymerized Attributable to monomers.

Examples of such compounds II are e.g. p-tert-butyl styrene, Esters of 3 to 6 carbon atoms having α, β-monoethylenic unsaturated carboxylic acids and more than 12 carbon atoms (usually alkanols containing up to 30 carbon atoms, such as e.g. Stearyl acrylate. But also esters from vinyl alcohol or allyl alcohol and having more than 12 carbon atoms (usually up to 30 carbon atoms) Alkane carboxylic acids, e.g. Vinyl stearate, are such compounds II. However, the copolymerizable compounds II include also macromonomers such as oligopropene acrylate. Are very general Macromonomer polymeric or oligomeric compounds, at least a, mostly terminal, ethylenically unsaturated double bond exhibit. Your relative number average molecular weight should be preferred for usability as a possible compound II not exceed 100,000. As a rule, this will relative number average molecular weight 1000 to 50,000 or 2000 to 50000. Macromonomers are known to the person skilled in the art. Their production is in Makromol, for example. Chem. 223 (1994) Pp. 29 to 46. Generally come as copolymerizable Compounds II such monomers into consideration molar solubility at 25 ° C and 1 bar in water is less than the corresponding molar solubility of lauryl acrylate (partially can also lauryl acrylate itself as a possible compound II be used). Such monomers are e.g. also methacryloyl polybutyl acrylate AB-6 and the methacryloyl polystyrene AS-6 from Toa Gasei Kagaku KK (JP), both of which are number average have a relative molecular weight of 6000. But also Polyol 130 from Hüls AG (a stereospecific, low-viscosity Polybutadiene (75% 1,4-cis, 24% 1,4-trans, 1% vinyl), whose dynamic viscosity at 20 ° C is 3000 mPa · s) and Polyol 110 from Hüls AG (a stereospecific, low viscosity Polybutadiene (75% 1,4-cis, 24% 1,4-trans, 1% vinyl), its dynamic viscosity at 20 ° C 3000 mPa · s) form as Compounds which can be used as macromonomers II.

Of course, with correspondingly low solubility in water, higher molecular compounds which do not have an ethylenically unsaturated group can also form suitable compounds II. Acronal® A 150 F, a poly-n-butyl acrylate from BASF AG, whose 50% strength by weight solution in ethyl acetate at 23 ° C. and 1 atm has a viscosity (determined in accordance with ISO 3219, DIN 53 019, is an example of this 250 s ^-1 ) of 33 mPa · s.

But also PnBA, a high temperature (120 ° C) solution (isopropanol) polymer of n-butyl acrylate with one at 25 ° C in isopropanol certain K value of 24 comes in as a possible compound II Consideration. The K value is a relative viscosity number, which in Analogy to DIN 53 726 is determined. It includes the flow rate of the pure solvent relative to the flow rate the 0.1 wt .-% solution of the polymer in same solvent (see also cellulose chemistry, vol. 13 (1932), Pp. 58-64, and Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 23, pp. 967-968). The K value is a measure of the middle Molecular weight of a polymer. A high K value corresponds to a high average molecular weight.

However, possible compounds II are also resins such as rosin resins (cf. Ullmanns Encykl. Techn. Chem. 4th edition (1976), Vol. 12, pp. 525-538) and hydrocarbon resins (see Encycl. Polym. Sci. Closely. (1987) Vol. 7, pp. 758-782), e.g. Kristalex F 85 from Hercules. Foral® 85 E is an example Glycerol ester of highly hydrogenated rosin (softening point: 86 ° C) from Hercules.

But also other water-insoluble, oil-soluble substances such as aliphatic and aromatic hydrocarbons (e.g. hexadecane), oil-soluble silicone compounds, film-forming aids or plasticizers such as Plastilit® 3060 (a polypropylene glycol alkylphenyl ether Plasticizers) come as possible compounds II (the often used in the form of mixtures). Of course, molecular compounds can also be used as compounds II (e.g. water-insoluble mercaptans) become. Based on the amount of radical according to the invention their proportion is usually to be polymerized Do not exceed 2% by weight.

The preparation of the aqueous required according to the invention Emulsion I can do so in a simple manner known per se take place that the compounds I and II producing them together mixes and first in a simple way in an emulsifier stirred in solution-containing aqueous solution and so an aqueous Monomer macro emulsion generated. The aqueous emulsifier solution also pH buffer substances such as sodium hydrogen carbonate added that contain the pH of the aqueous Medium cheap during the later radical polymerization shape. Anionic and / or are preferably used as emulsifiers nonionic emulsifiers used. In principle, too the use of cationic emulsifiers possible. Everyone can those emulsifiers are used, their possible application for radical aqueous macro emulsion polymerization is known (oil in water emulsifiers).

Common emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 50, alkyl radical: C ₄ to C ₉ ), ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl radical: C ₈ to C ₃₆ ), as well as alkali and ammonium salts of alkyl sulfates (alkyl radical: C ₈ to C ₁₂ ), of sulfuric acid semi-esters of ethoxylated alkanols (EO degree: 4 to 30, alkyl radical: C ₁₂ to C ₁₈ ) and ethoxylated alkyl phenols (EO degree: 3 to 50, alkyl radical: C ₄ to C ₉ ), of alkyl sulfonic acids (alkyl radical: C ₁₂ to C ₁₈ ) and of alkylarylsulfonic acids (alkyl radical: C ₉ to C ₁₈ ). Further suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208.

worin R¹ und R² Wasserstoff oder C₄- bis C₂₄-Alkyl bedeuten und nicht gleichzeitig Wasserstoff sind, und X und Y Alkalimetallionen und/oder Ammoniumionen sein können, erwiesen. In der Formel I bedeuten R¹ und R² bevorzugt lineare oder verzweigte Alkylreste mit 6 bis 18 C-Atomen oder Wasserstoff, und insbesondere mit 6, 12 und 16 C-Atomen, wobei R¹ und R² nicht beide gleichzeitig Wasserstoff sind. X und Y sind bevorzugt Natrium, Kalium oder Ammoniumionen, wobei Natrium besonders bevorzugt ist. Besonders vorteilhaft sind Verbindungen I in denen X und Y Natrium, R¹ ein verzweigter Alkylrest mit 12 C-Atomen und R² Wasserstoff oder R¹ ist. Häufig werden technische Gemische verwendet, die einen Anteil von 50 bis 90 Gew.-% des monoalkylierten Produktes aufweisen, beispielsweise Dowfax® 2A1 (Warenzeichen der Dow Chemical Company). Die Verbindungen I sind allgemein bekannt, z.B. aus der US-A 4,269,749, und im Handel erhältlich.Compounds of the general formula I have also been found to be suitable emulsifiers

wherein R ¹ and R ^{2 are} hydrogen or C ₄ - to C ₂₄ -alkyl and are not simultaneously hydrogen, and X and Y can be alkali metal ions and / or ammonium ions. In the formula I, R ¹ and R ^{2 are} preferably linear or branched alkyl radicals having 6 to 18 carbon atoms or hydrogen, and in particular having 6, 12 and 16 carbon atoms, where R ¹ and R ^{2 are} not both hydrogen at the same time. X and Y are preferably sodium, potassium or ammonium ions, with sodium being particularly preferred. Compounds I in which X and Y are sodium, R ^{1 is} a branched alkyl radical having 12 C atoms and R ^{2 is} hydrogen or R ¹ are particularly advantageous. Technical mixtures are frequently used which have a proportion of 50 to 90% by weight of the monoalkylated product, for example Dowfax® 2A1 (trademark of the Dow Chemical Company). The compounds I are generally known, for example from US Pat. No. 4,269,749, and are commercially available.

According to the invention, the amount of emulsifier is expediently chosen so that that in the ultimately resulting aqueous emulsion I within the critical phase of micelle formation in the aqueous phase emulsifiers used are essentially not exceeded. Based on the amount contained in the aqueous emulsion I. Compounds I and II are usually in the amount of emulsifier Range from 0.1 to 5% by weight.

Since the aforementioned emulsifiers also the disperse distribution in the ultimately resulting aqueous polymer dispersion stabilize, they can also add protective colloids to the Be given. These are able to withstand the surface tension of Water can hardly be reduced and usually show above 1000 lying relative molecular weights. Possible protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or copolymers containing vinylpyrrolidone. A detailed one A description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular substances, Georg-Thieme-Verlag, Stuttgart, 1961, Pp. 411 to 420.

The aqueous monomer macroemulsion obtainable as described can then be used according to the invention in the usual manner aqueous emulsion I can be homogenized (see P.L. Tang, E.D. Sudol, C.A. Silebi and M.S. El-Aasser in the Journal of Applied Polymer Science, Vol. 43, pp. 1059-1066 [1991]). Usually will high pressure homogenizers are used. The fine distribution The components in these machines are characterized by a high achieved local energy input. There are two variants in this regard especially proven.

In the first variant, the aqueous monomer macro emulsion compressed to over 1000 bar by means of a piston pump and then relaxed through a narrow gap. The effect is based here on an interplay of high shear and pressure gradients and cavitation in the gap. An example of a high pressure homogenizer, that works on this principle is the Niro-Soavi High pressure homogenizer, type NS1001L Panda.

In the second variant, the compressed aqueous monomer macro emulsion via two opposing nozzles into one Mixing chamber relaxed. The fine distribution effect is here all of the hydrodynamic conditions in the mixing chamber dependent. An example of this type of homogenizer is the microfluidizer Type M 120 E from Microfluidics Corp. In this high pressure homogenizer becomes the aqueous monomer macro emulsion by means of a pneumatically operated piston pump at pressures of compressed up to 1200 bar and via a so-called "interaction chamber "relaxes. In the" interaction chamber "the emulsion jet divided into two beams in a micro-channel system, which are brought together at 180 °. Another one Example of one working according to this type of homogenization The homogenizer is the Nanojet Type Expo from Nanojet Engineering GmbH. However, with Nanojet instead of a fixed channel system two homogenizing valves built in, mechanically adjusted can be.

In addition to the principles mentioned above, homogenization but e.g. also by using ultrasound (e.g. Branson Sonifier II 450) can be generated. The fine distribution is based here on cavitation mechanisms. The quality of the sound field generated aqueous emulsion I depends not only on the introduced Sound power, but also by other factors such as. the intensity distribution of the ultrasound in the mixing chamber, the residence time, the temperature and the physical Properties of the substances to be emulsified, for example of the Toughness, interfacial tension and vapor pressure. The resulting droplet size depends on of concentration of the emulsifier and of the homogenization energy and is e.g. through appropriate change the homogenization pressure or the corresponding Ultrasound energy selectively adjustable.

The average size of the droplets of the disperse phase of the aqueous emulsion I to be used according to the invention can be determined on the principle of quasi-elastic dynamic light scattering (the so-called z-average droplet diameter d _z the unimodal analysis of the autocorrelation function). In the examples in this document, a Coulter N4 Plus Particle Analyzer from Coulter Scientific Instruments was used (1 bar, 25 ° C.). The measurements were carried out on dilute aqueous emulsions I whose content of non-aqueous constituents was 0.01% by weight. The dilution was carried out using water which had previously been saturated with the compounds I and II contained in the aqueous emulsion. The latter measure is intended to prevent a change in the droplet diameter associated with the dilution.

According to the invention, the values determined in this way are for d _z normally ≤ 500 nm, frequently ≤ 400 nm d _z range from 100 nm to 300 nm or from 100 nm to 200 nm d _{z of} the aqueous emulsion I to be used according to the invention I 40 40 nm.

Usually contain those to be used according to the invention aqueous emulsions I, based on the compounds contained I, at least 0.5% by weight of compounds II. An upper one Bound for the amount of contained in this way Connections II do not exist. This statement applies in particular then, if it is only in the compounds II used is about those that themselves are at least one radical have polymerizable unsaturated group. As a general rule however, the content of compounds II obtained in this way Do not exceed 200% by weight and are often ≤ 100% by weight. Embodiments according to the invention are also those in which the content of compounds II 1 to as obtained above 50% by weight, or 2 to 30% by weight, or 5 to 15% by weight.

The total content of compounds I and II is normally in the aqueous emulsion I not more than 50% by weight to the aqueous emulsion I. With a higher total content Compounds I and II usually go an inappropriate one Resistance to flow accompanied by a polydisperse reduction (In the simplest case bimodal) adjustment of the droplet diameter distribution the disperse phase required.

In principle, all those come as part of the inflow II Compounds I into consideration, which are also part of the aqueous Emulsion I can be. As a rule, you choose the one in inflow II contained compounds I, however, so that their individual molar solubility in water under the polymerization conditions is greater than the corresponding water solubility of the below Polymerization conditions most poorly water soluble Compound I of the aqueous emulsion I. Preferably, the individual molar solubility of compounds I of feed II but worse under the polymerization conditions in water be as in the dispersed droplets of the aqueous Emulsion I.

Advantageously, inlet II only comprises compounds I. This embodiment variant of the method according to the invention is Particularly favorable if the solids content is high resulting aqueous polymer dispersion is desired. In principle, however, there is also an aqueous monomer macroemulsion as feed II of compounds I into consideration. In the latter Case, all those emulsifiers can be used that already mentioned in connection with the aqueous emulsion I. were. According to the invention e.g. up to 10% by weight, up to 20% by weight, or up to 30% by weight, or up to 40% by weight, or up to up to 50% by weight, or up to 60% by weight, or up to 70% by weight, or up to 80% by weight, or up to 90% by weight or more or the Total amount of the aqueous emulsion I as the polymerization vessel at least one feed I can be fed continuously.

The method according to the invention can be done in the simplest way be carried out that something in the polymerization vessel Submits water, the submitted water to the polymerization temperature warmed and then over spatially separated Feeds the aqueous emulsion I and the radical polymerization initiator, usually as an aqueous solution, under Maintenance of the polymerization to the polymerization vessel feeds continuously. In this case, you will benefit from the feed II, which is essential according to the invention, is synchronous with the aqueous feed Add emulsion I.

However, the process according to the invention will often be carried out in such a way that that up to 50 wt .-%, or up to 30 wt .-%, or up 15% by weight of the aqueous emulsion I, optionally with addition of water, placed in the polymerization vessel, the template on the Heated polymerization temperature, radical polymerization initiator adds, the resulting mixture polymerized and then the remaining amount of the aqueous emulsion I under Maintenance of the polymerization in the polymerization vessel feeds continuously, and this feed by a preferably synchronous continuous supply of polymerization initiator as well accompanied by a synchronous feed of inlet II. Basically but can also the total amount of radical polymerization initiator be placed in the polymerization vessel.

The total molar amount of compounds I, which are used as part of feed II (molar Amount A), ≤ the total molar amount of compounds I, which are used as part of the aqueous emulsion I. (molar amount B). However, it can also be two or more times this amount. Embodiments according to the invention are accordingly those processes in which the molar amount A up to 300% or up to 100%, or up to 75%, or up to 50% or is up to 25% or up to 10% of the molar amount B. The The lower limit is often 5%.

In principle, radical polymerization initiators come consider all those who are capable of a radical Trigger polymerization. It can be both peroxides, hydroperoxides and azo compounds. They can be both oil-soluble and water-soluble.

Preferably for the inventive method radical polymerization initiators with increased water solubility used. Examples of such polymerization initiators are e.g. peroxodisulfuric acid and its Ammonium and alkali metal salts as well as hydrogen peroxide and tert-butyl hydroperoxide. Of course, as such water-soluble radical polymerization initiators too combined systems consisting of at least one reducing agent and composed of at least one peroxide and / or hydroperoxide are used. Examples of such combinations are e.g. tert-butyl hydroperoxide / sodium metal salt of hydroxymethanesulfinic acid and hydrogen peroxide / ascorbic acid. Frequently the combined systems additionally comprise a small amount a metal compound soluble in the aqueous medium, the metallic Component can occur in several severity levels. Examples of such systems are e.g. Ascorbic acid / iron (II) sulfate / hydrogen peroxide or sodium sulfite / iron (II) sulfate / hydrogen peroxide. Of course, in the aforementioned systems instead of ascorbic acid also the sodium metal salt of Hydroxymethanesulfinic acid, sodium bisulfite or sodium metal bisulfite be used. Furthermore, in the aforementioned Systems instead of hydrogen peroxide tert-butyl hydroperoxide or alkali metal peroxydisulfates and / or ammonium peroxydisulfates be applied. Instead of a water soluble Iron (II) salt is often a combination of water-soluble Fe / V salts used.

Based on the radical monomers to be polymerized usually 0.1 to 10% by weight, often 0.5 to 5% by weight radical polymerization initiators used.

The polymerization temperature depends on the invention Process usually according to the decay temperature of the used radical polymerization initiator. Redox initiator systems usually disintegrate at particularly low temperatures. Typical polymerization temperatures are 0 ° C to 95 ° C, often 30 ° C to 90 ° C and often 50 ° C to 85 ° C. When using elevated The polymerization temperature can also be up to 120 ° C and more. Usually at normal pressure (1 bar) polymerized.

The inlets can be used in the process according to the invention the polymerization reactor from above, from the side or through be fed to the reactor floor.

The advantage of the procedure according to the invention is attributed without claim to validity that the uninitiated Monomer droplets are still like a monomer reservoir Release monomers to the aqueous phase, but will these monomers barely get in through radical polymerization the initiated monomer droplets consumed because in the form of Inlet II in the aqueous phase a radical oversupply polymerizable compounds I that do not contain the monomer mini-emulsion droplets come from, is set. The possible Reservoir function of the uninitiated monomer miniemulsion droplets is therefore not claimed, which means a more uniform Product results.

Another advantage of the method according to the invention is that Possibility of realizing increased polymer volume fractions in the aqueous polymer dispersion (up to 60 or 70 vol .-% u. more). With regard to the same, it proves advantageous that the method according to the invention generally, with respect to Distribution function of the diameter of the dispersed polymer particles, polydisperse or polymodal aqueous polymer dispersions leads.

Examples A) Preparation of suitable for the inventive method aqueous emulsions I a) to t)

A:

Hochdruckhomogenisator Niro Soavi, Typ NS 1001 L Panda; zur Homogenisierung der wäßrigen Monomerenmakroemulsionen wurde jeweils ein Durchlauf bei 850 bar durchgeführt;

B:

Microfluidizer, Typ M 120 der Fa. Microfluidics Corp.; zur Homogenisierung wurde jeweils ein Durchlauf bei 1000 bar durchgeführt;

C:

Hochdruckhomogenisator Nanojet, Modell Expo; zur Homogenisierung wurde jeweils ein Durchlauf bei 850 bar durchgeführt;

D:

Ultraschall (Branson Sonifier II 450); 1 Liter der wäßrigen Monomerenmakroemulsion wurde unter Rühren jeweils 5 min mit den Einstellungen Duty Cycle 25 %, Output Control 10 und jeweils 20 min bei Duty Cycle 100 % und Output Control 10 beschallt.

General manufacturing instructions:
An aqueous solution of water, 15% by weight aqueous sodium lauryl sulfate solution and optionally sodium bicarbonate was introduced. An inlet 1 consisting of compounds I and II was added to this aqueous solution 1 with stirring, and the resulting mixture was stirred for a further 10 minutes after the addition had ended. The resulting aqueous monomer macroemulsions were then homogenized using one of the following homogenization methods A to D to give an aqueous monomer microemulsion:

A:

High pressure homogenizer Niro Soavi, type NS 1001 L Panda; To homogenize the aqueous monomer macroemulsions, a run was carried out at 850 bar;

B:

Microfluidizer, type M 120 from Microfluidics Corp .; one pass was carried out at 1000 bar for homogenization;

C:

High pressure homogenizer Nanojet, model Expo; one pass was carried out at 850 bar each for homogenization;

D:

Ultrasound (Branson Sonifier II 450); 1 liter of the aqueous monomer macroemulsion was sonicated for 5 minutes with the settings Duty Cycle 25%, Output Control 10 and 20 minutes each with Duty Cycle 100% and Output Control 10.

To characterize the aqueous monomer miniemulsion obtained, its d _z [nm] determined.

Table 1 shows the results obtained and the composition (all data are given in grams) of the solutions 1 and feeds 2 used in each case.
Table 1 also shows the homogenizer used.

B) Production according to the invention and not according to the invention aqueous polymer dispersions

General manufacturing instructions:

First, as in Example A), aqueous emulsions I were produced. In all cases, the homogenization was carried out according to the method of homogenization A.

Then a certain amount was added to the polymerization vessel Submitted water and heated to 85 ° C.

Then the heated template was at once 10% by weight of aqueous emulsion I and 15% by weight of one Feed 2 (aqueous sodium peroxodisulfate solution as radical Polymerization initiator) added and that resulting mixture polymerized at 85 ° C for 15 min.

The polymerization vessel was then started at the same time the remaining amount of the aqueous emulsion I as feed I. (within 2 h), the remaining amount of feed 2 (within of 2 h and 30 min) and optionally one of compounds I existing inlet II (within 2 h) under Maintenance of 85 ° C via spatially separated inlets fed continuously. After the inlets were finished the reaction mixture was kept under stirring at 85 ° C. for 1 h and then cooled to 25 ° C.

To characterize the resulting aqueous polymer dispersions was their solids content (FG, in % By weight, based on the aqueous polymer dispersion), the pH of the aqueous dispersion medium, the so-called LD value (this is the light transmission of an FG of 0.01% by weight of dilute aqueous polymer dispersion (determined with a layer thickness of 2.5 cm) relative to the light transmission of pure water (LD value = 100)), the Contained amount of macrocoagulate KG (percentage weight of the filtration of the aqueous polymer dispersion remaining through a filter of 125 µm mesh size Residue, based on the solids content of the aqueous Polymer dispersion) and that after the aforementioned filtration amount of specks S (microcoagulate; the Quantity was determined by optical assessment of a a dry thickness of 60 microns film of the aqueous Polymer dispersion, the film formation 10 ° C above however, their minimum film-forming temperature (DIN 53 787) is not occurred below 20 ° C; 1 = speck free, 5 = worst Assessment).

The quotient Q = d ₉₀ -d ₁₀ / d _{50 was} determined as a measure for characterizing the width of the diameter distribution of the dispersed polymer particles, where d _{m is} the diameter which is not exceeded by m% by weight of the dispersed polymer particles. As a measure of the chemical uniformity of the dispersed polymer particles, their mass density distribution was examined. Both the polymer particle diameter distribution and the mass density distribution were investigated in the analytical ultracentrifuge using the H ₂ O / D ₂ O sedimentation analysis and using dynamic density gradients. A detailed description of the measurement methods by W. Mächtle can be found in "Analytical Ultracentrifugation in Biochemistry and Polymer Science, SE Harding et al (Eds.), Royal Society of Chemistry, Cambridge, England (1992), Chapter 10".

The following are the compositions used (amounts in grams) and the results obtained in detail listed.

Vorlage:

300 g Wasser;

Lösung 1:

738,4 g Wasser, 1,6 g Natriumhydrogencarbonat, 32 g einer 15 gew.-%igen wäßrigen Natriumlaurylsulfatlösung;

Zulauf 1:

400 g n-Butylacrylat (I), 160 g Stearylacrylat (II);

Zulauf 2:

150 g Wasser, 4 g Natriumperoxodisulfat;

Zulauf II:

240 g n-Butylacrylat (I);

FG:

39 Gew.-%;

pH:

: 3,0;

LD:

58;

d _z

(wäßrige Emulsion I): 177 nm;

d _z

(resultierende Polymerisatdispersion D1): 235 nm;

KG:

0 Gew.-%;

S:

1;

Q:

0,986;

D1:

Template:

300 g water;

Solution 1:

738.4 g of water, 1.6 g of sodium hydrogen carbonate, 32 g of a 15% by weight aqueous sodium lauryl sulfate solution;

Inlet 1:

400 g n-butyl acrylate (I), 160 g stearyl acrylate (II);

Inlet 2:

150 g water, 4 g sodium peroxodisulfate;

Inlet II:

240 g of n-butyl acrylate (I);

FG:

39% by weight;

pH:

: 3.0;

LD:

58;

d _e.g.

(aqueous emulsion I): 177 nm;

d _e.g.

(resulting polymer dispersion D1): 235 nm;

KG:

0% by weight;

S:

1;

Q:

0.986;

The mass density of the dispersed polymer particles d 25/4 extends over the range from 1.019 g / cm ³ to 1.044 g / cm ³ .

VD1:

Vorlage, Lösung 1 und Zulauf 2 wie für D1. Zulauf 1 bestand jedoch aus 640 g n-Butylacrylat (I) und 160 g Stearylacrylat (II); dafür wurde kein Zulauf II angewendet.

FG:

37,6 Gew.-%;

pH:

3,3;

LD:

28;

d _z

(wäßrige Emulsion I): 344 nm;

d _z

(resultierende Polymerisatdispersion VD1): 287 nm;

KG:

8,5 Gew.-%;

S:

3;

This indicates that neither pure n-butyl acrylate is present in the course of the polymerization
(d 25/4 = 1.06 g / cm ³ ) still pure polystearyl acrylate (d 25/4 = 0.94 g / cm ³ ) was formed.
KG and S values indicate that D1 was essentially free of coagulum.

VD1:

Submission, solution 1 and feed 2 as for D1. Feed 1, however, consisted of 640 g of n-butyl acrylate (I) and 160 g of stearyl acrylate (II); no inlet II was used for this.

FG:

37.6% by weight;

pH:

3.3;

LD:

28;

d _e.g.

(aqueous emulsion I): 344 nm;

d _e.g.

(resulting polymer dispersion VD1): 287 nm;

KG:

8.5% by weight;

S:

3;

D2:

Vorlage, Lösung 1 und Zuläufe 2, II wie für D1. Zulauf 1 bestand jedoch aus 280 g n-Butylacrylat (I) und 280 g Stearylacrylat (II);

FG:

39,4 Gew.-%;

pH:

2,9;

LD:

52;

d _z

(wäßrige Emulsion I): 197 nm;

d _z

(resultierende Polymerisatdispersion D2): 234 nm;

KG:

2 Gew.-%;

S:

1;

Q:

1,437;

d 25 / 4 :

0,975 g/cm³ bis 1,045 g/cm³;

D2

unterscheidet sich von D1 lediglich durch einen erhöhten Anteil an Stearylacrylat. Bildung von Polystearylacrylat wurde dennoch nicht beobachtet.

VD2:

Wie D2, Zulauf II wurde jedoch ersatzlos weggelassen.

FG:

31,8 Gew.-%;

pH:

3,7;

LD:

39;

d _z

(wäßrige Emulsion I): 223 nm;

d _z

(resultierende Polymerisatdispersion VD2): 228 nm;

KG:

3,8 Gew.-%;

S:

3;

The aqueous polymer dispersion VD1 had a considerable amount of floating coagulate, which consisted of pure polystearyl acrylate according to DSC (differential scanning calorimetry) analysis. The gross compositions of D1 and VD1 are identical.

D2:

Template, solution 1 and inlets 2, II as for D1. Feed 1, however, consisted of 280 g of n-butyl acrylate (I) and 280 g of stearyl acrylate (II);

FG:

39.4% by weight;

pH:

2.9;

LD:

52;

d _e.g.

(aqueous emulsion I): 197 nm;

d _e.g.

(resulting polymer dispersion D2): 234 nm;

KG:

2% by weight;

S:

1;

Q:

1,437;

d 25/4:

0.975 g / cm ³ to 1.045 g / cm ³ ;

D2

differs from D1 only in an increased proportion of stearyl acrylate. However, no formation of polystearyl acrylate was observed.

VD2:

Like D2, inlet II was omitted without replacement.

FG:

31.8% by weight;

pH:

3.7;

LD:

39;

d _e.g.

(aqueous emulsion I): 223 nm;

d _e.g.

(resulting polymer dispersion VD2): 228 nm;

KG:

3.8% by weight;

S:

3;

VD3:

Vorlage: 200 g Wasser;

Lösung 1:

838,4 g Wasser, 1,6 g Natriumhydrogencarbonat, 32 g einer 15 gew.-%igen wäßrigen Natriumlaurylsulfatlösung;

Zulauf 1:

520 g n-Butylacrylat (I), 280 g Stearylacrylat (II);

Zulauf 2:

150 g Wasser, 4 g Natriumperoxodisulfat;

The aqueous polymer dispersion VD2, like VD1, had a considerable amount of floating polystearyl acrylate.

VD3:

Initial charge: 200 g water;

Solution 1:

838.4 g of water, 1.6 g of sodium hydrogen carbonate, 32 g of a 15% by weight aqueous sodium lauryl sulfate solution;

Inlet 1:

520 g n-butyl acrylate (I), 280 g stearyl acrylate (II);

Inlet 2:

150 g water, 4 g sodium peroxodisulfate;

Inlet II:

FG:

39.2% by weight:

pH:

3.2;

LD:

31;

d _e.g.

(aqueous emulsion I): 253 nm;

d _e.g.

(resulting polymer dispersion VD3): 258 nm;

KG:

5.0% by weight;

S:

3;

D3: Vorlage:

300 g Wasser;

Lösung 1:

834,4 g Wasser, 1,6 g Natriumhydrogencarbonat, 32 g einer 15 gew.-%igen wäßrigen Natriumlaurylsulfatlösung;

Zulauf 1:

560 g Styrol (I); 64 g PnBA (II);

Zulauf 2:

150 g Wasser, 4 g Natriumperoxodisulfat;

Zulauf II:

240 g Styrol (I);

FG: :

39,2 Gew.-%;

pH:

6,5;

LD:

20;

d _z

(wäßrige Emulsion I): 210 nm;

d _z

(resultierende Polymerisatdispersion): 245 nm;

KG:

1,6 Gew.-%;

S:

2;

d 25 / 4:

1,050 g/cm³ bis 1,054 g/cm³;

The aqueous polymer dispersion VD3 had the same gross composition as D2, but in contrast to D2 showed considerable amounts of floating polystearyl acrylate.

D3: Template:

300 g water;

Solution 1:

834.4 g of water, 1.6 g of sodium hydrogen carbonate, 32 g of a 15% by weight aqueous sodium lauryl sulfate solution;

Inlet 1:

560 g styrene (I); 64 g PnBA (II);

Inlet 2:

150 g water, 4 g sodium peroxodisulfate;

Inlet II:

240 g styrene (I);

FG::

39.2% by weight;

pH:

6.5;

LD:

20;

d _e.g.

(aqueous emulsion I): 210 nm;

d _e.g.

(resulting polymer dispersion): 245 nm;

KG:

1.6% by weight;

S:

2;

d 25/4:

1.050 g / cm ³ to 1.054 g / cm ³ ;

VD4:

Vorlage, Lösung 1 und Zulauf 2 wie für D3. Zulauf 1 bestand jedoch aus 800 g Styrol (I) und 64 g PnBA; dafür wurde kein Zulauf II angewendet:

FG:

39 Gew.-%;

pH:

7,2;

LD:

16;

d _z

(wäßrige Emulsion I): 237 nm;

d _z

(resultierende Polymerisatdispersion VD4): 258 nm;

KG:

3,0 Gew.-%;

S:

3;

The polymer particle diameter distribution was markedly bimodal. The d 25/4 values of PnBA and polystyrene are 1.05 and 1.06 g / cm ^3, respectively.

VD4:

Template, solution 1 and inlet 2 as for D3. Feed 1, however, consisted of 800 g of styrene (I) and 64 g of PnBA; no inlet II was used for this:

FG:

39% by weight;

pH:

7.2;

LD:

16;

d _e.g.

(aqueous emulsion I): 237 nm;

d _e.g.

(resulting polymer dispersion VD4): 258 nm;

KG:

3.0% by weight;

S:

3;

D4: Vorlage:

300 g Wasser;

Lösung 1:

834,4 g Wasser, 1,6 g Natriumhydrogencarbonat, 32 g einer 15 gew.-%igen wäßrigen Natriumlaurylsulfatlösung;

Zulauf 1:

560 g Styrol (I); 64 g AB-6 (II);

Zulauf 2:

150 g Wasser, 4 g Natriumperoxodisulfat;

Zulauf II:

240 g Styrol (I);

FG:

39,4 Gew.-%;

pH :

5.1:

LD:

18;

d _z

(wäßrige Emulsion I): 170 nm;

d _z

(resultierende Polymerisatdispersion) : 239 nm;

KG:

0,9 Gew.-%;

S:

2;

VD5 :

:Vorlage, Lösung 1 und Zulauf 2 wie für D4. Zulauf 1 bestand jedoch aus 800 g Styrol (I) und 64 g AB-6; dafür wurde kein Zulauf II angewendet;

FG:

39,1 Gew.-%;

pH:

6.2;

LD:

11;

d _z

(wäßrige Emulsion I): 282 nm;

d _z

(resultierende Polymerisatdispersion): 260 nm;

KG:

3,1 Gew.-%;

S:

2;

Compared to D3, VD4 had an increased proportion of macro and micro coagulum.

D4: Template:

300 g water;

Solution 1:

834.4 g of water, 1.6 g of sodium hydrogen carbonate, 32 g of a 15% by weight aqueous sodium lauryl sulfate solution;

Inlet 1:

560 g styrene (I); 64 g AB-6 (II);

Inlet 2:

150 g water, 4 g sodium peroxodisulfate;

Inlet II:

240 g styrene (I);

FG:

39.4% by weight;

pH:

5.1:

LD:

18;

d _e.g.

(aqueous emulsion I): 170 nm;

d _e.g.

(resulting polymer dispersion): 239 nm;

KG:

0.9% by weight;

S:

2;

VD5:

: Template, solution 1 and inlet 2 as for D4. Feed 1, however, consisted of 800 g of styrene (I) and 64 g of AB-6; no inlet II was used for this;

FG:

39.1% by weight;

pH:

6.2;

LD:

11;

d _e.g.

(aqueous emulsion I): 282 nm;

d _e.g.

(resulting polymer dispersion): 260 nm;

KG:

3.1% by weight;

S:

2;

Compared to D4, VD5 had an increased proportion of macrocoagulate on. The DSC analysis of the macrocoagulum indicated a significant enrichment in AB-6 compared to AB-6 Content of the filtered aqueous polymer dispersion educated film.

Table 2 below shows further exemplary embodiments D5 to D15 to demonstrate the broad applicability of the method according to the invention and to demonstrate the possibility of obtaining high solids contents. The units used for the individual sizes correspond to the units used in the previous examples.

Claims (30)

1. A process for preparing an aqueous polymer dispersion by free-radically initiated polymerization of free-radically polymerizable compounds whose individual solubility in water under the conditions of the free-radically initiated polymerization is at least 0.001 % by weight, based on the respective saturated aqueous solution (compounds I), whose disperse polymer particles comprise, in addition to the compounds I, at least one compound II whose solubility in water under the conditions of the free-radically initiated polymerization is less than 0.001 % by weight, based on the respective saturated aqueous solution, and in which process a mixture consisting of a molar amount B of the compounds I and of the at least one compound II is used to produce an oil-in-water emulsion I whose disperse phase consists predominantly of droplets with a diameter ≤ 500 nm, and in which at least a portion of the aqueous emulsion I is supplied continuously as a feed stream I to the polymerization vessel in the course of continuing free-radical polymerization, wherein the continuous feed stream I is synchronously accompanied by at least one feed stream II, with the proviso that the at least one feed stream II is a feed stream of a molar amount A of the compounds I and/or is an oil-in-water emulsion II of a molar amount A of the compounds I, whose disperse phase consists predominantly of droplets with a diameter ≥ 1000 nm, and the molar amount A is 5 to 300% of the molar amount B.
2. A process as claimed in claim 1, wherein the compounds I are exclusively monomers containing at least one ethylenically unsaturated group.
3. A process as claimed in claim 1, wherein the compounds I are a mixture of molecular weight regulators and monomers comprising at least one ethylenically unsaturated group.
4. A process as claimed in claim 1, wherein the compounds I consist of

   A) from 80 to 100 parts by weight

   of at least one monomer from the group consisting of styrene, α-methylstyrene, vinyltoluenes, esters of α,β-monoethylenically unsaturated C₃-C₆ carboxylic acides and C₁-C₁₂ alkanols, butadiene, and vinyl esters and allyl esters of C₁-C₁₂ alkanecarboxylic acids (monomers A), and

   B) from 0 to 20 parts by weight

   of other compounds I, containing at least one ethylenically unsaturated group (monomers B)

   and, if desired, from 0.01 to 2 % by weight, based on the sum of the monomers A and B, of molecular weight regulators I.
5. A process as claimed in claim 4, wherein the monomers A are selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate and styrene.
6. A process as claimed in claim 4 or 5, wherein the monomers B are selected from the group consisting of acrylamide, methacrylamide, acrylic acid, acrylonitrile, methacrylonitrile, 2-acrylamido-2-methylpropanesulfonic acid, vinylpyrrolidone, hydroxyethyl acrylate, hydroxymethyl hydroxypropyl acrylate, hydroxypropyl methacrylate, quaternized vinylimidazole, N,N-dialkylaminoalkyl (meth)acrylate, N,N-dialkylaminoalkyl(meth)acrylamide, trialkylammoniumalkyl (meth)acrylate and trialkylammoniumalkyl(meth)acrylamide.
7. A process as claimed in claim 1, wherein the compounds I are composed of from 70 to 100 % by weight of esters of acrylic and/or methacrylic acid with C₁-C₁₂ alkanols and/or styrene.
8. A process as claimed in claim 1, wherein the compounds I are composed of from 70 to 100 % by weight of styrene and/or butadiene.
9. A process as claimed in claim 1, wherein the compounds I are composed of from 70 to 100 % by weight of vinyl chloride and/or vinylidene chloride.
10. A process as claimed in claim 1, wherein the compounds I are composed of from 40 to 100 % by weight of vinyl acetate, vinyl propionate and/or ethylene.
11. A process as claimed in any of claims 1 to 10, wherein the compounds II contain at least one monoethylenically unsaturated group.
12. A process as claimed in claim 11, wherein the compounds II are selected from the group consisting of esters of α,β-monoethylenically unsaturated C₃-C₆ carboxylic acids and alkanols having more than 12 carbon atoms, esters of vinyl alcohol or allyl alcohol and alkanecarboxylic acids having more than 12 carbon atoms, and macromonomers.
13. A process as claimed in any of claims 1 to 10, wherein the compounds II contain no monoethylenically unsaturated group.
14. A process as claimed in any of claims 1 to 10, wherein the compounds II are a mixture of compounds II containing at least one monoethylenically unsaturated group and compounds II containing no monoethylenically unsaturated group.
15. A process as claimed in any of claims 1 to 10, wherein the compounds II comprise molecular weight regulators.
16. A process as claimed in any of claims 1 to 15, wherein d _z of the droplets of the aqueous emulsion I is ≤ 500 nm.
17. A process as claimed in any of claims 1 to 15, wherein d _z of the droplets of the aqueous emulsion I is from 40 nm to 400 nm.
18. A process as claimed in any of claims 1 to 15, wherein d _z of the droplets of the aqueous emulsion I is from 100 nm to 300 nm.
19. A process as claimed in any of claims 1 to 15, wherein d _z of the droplets of the aqueous emulsion I is from 100 nm to 200 nm.
20. A process as claimed in any of claims 1 to 19, wherein the aqueous emulsion I, based on the compounds II present, contains at least 0.5 % by weight of compounds II.
21. A process as claimed in any of claims 1 to 19, wherein the aqueous emulsion I, based on the compounds I present, contains from 1 to 200 % by weight of compounds II.
22. A process as claimed in any of claims 1 to 19, wherein the aqueous emulsion I, based on the compounds I present, contains from 2 to 100 % by weight of compounds II.
23. A process as claimed in any of claims 1 to 22, wherein the compounds I present in the feed stream II are selected such that their individual molal solubility in water under the polymerization conditions is greater than the corresponding water-solubility of that compound I of the aqueous emulsion I that is the least soluble in water under polymerization conditions.
24. A process as claimed in any of claims 1 to 23, wherein the individual solubility in water, under the polymerization conditions, of the compounds I present in the feed stream II is poorer than in the dispersed droplets of the aqueous emulsion I.
25. A process as claimed in any of claims 1 to 24, wherein the feed stream II consists exclusively of compounds I.
26. A process as claimed in any of claims 1 to 25, wherein the overall molar amount of compounds I that are employed as a constituent of the feed stream II (molar amount A) is greater than the overall molar amount of compounds I that are employed as a constituent of the aqueous emulsion I (molar amount B).
27. A process as claimed in any of claims 1 to 25, wherein the overall molar amount: of compounds I that are employed as a constituent of the feed stream II (molar amount A) is less than or equal to the overall molar amount of compounds I that are employed as a constituent of the aqueous emulsion I (molar amount B).
28. A process as claimed in any of claims 1 to 27, wherein water is charged to the polymerization vessel, the initial charge of water is heated to the polymerization temperature, and then, by way of spatially separate feeds, the aqueous emulsion I, the free-radical polymerization initiator and the feed stream II are supplied continuously to the polymerization vessel while the polymerization is maintained.
29. A process as claimed in any of claims 1 to 27, wherein, with or without the addition of water, up to 50 % by weight of the aqueous emulsion I is charged to the polymerization vessel, the initial charge is heated to the polymerization temperature, free-radical polymerization initiator is added, the resulting mixture is partially polymerized, and then the remainder of the aqueous emulsion I is supplied continuously to the polymerization vessel, while the polymerization is maintained, and this supply is accompanied by a preferably continuous supply of polymerization initiator and by a preferably synchronous supply of the feed stream II.
30. A process as claimed in any of claims 1 to 29, wherein a free-radical polymerization initiator is used which predominantly dissolves in the aqueous phase.